Utility of Magnetic Resonance Perfusion Imaging in Quantifying Active Tumor Fraction and Radiation Necrosis in Recurrent Intracranial Tumors

Diagnostic value and efficacy of multimodal magnetic resonance imaging in differentiating radiation necrosis from tumor recurrence in glioblastomas

BackgroundDistinguishing radiation necrosis (RN) from recurrent tumor (RT) in patients with gliomas treated with radiation therapy presents an important clinical dilemma.PurposeTo evaluate the diagnostic performance of multiparametric magnetic resonance imaging (MRI) techniques in distinguishing RN from RT in patients with histologically confirmed glioma treated previously with radiotherapy and chemotherapy or without chemotherapy using a combination of dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion MRI, diffusion tensor imaging (DTI), and MR spectroscopy (MRS).Material and MethodsPatients with glioma who developed a new enhancing mass after standard treatment were retrospectively evaluated. Conventional MRI, DTI, DSC, and MRS were performed. The region of interest (ROI) was manually drawn in the enhancing lesions, peri-lesional white matter edema, and the contralateral normal-appearing white matter. Apparent diffusion coefficient (ADC), fractional anisotropy (FA), relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), N-acetylaspartate (NAA), choline (Cho), creatine (Cr), NAA/Cr, Cho/NAA, and Cho/Cr were calculated. Two-tailed t-test and receiver operating characteristic (ROC) curve analysis were performed.ResultsIn total, 34 patients with RT and 25 with RN met our inclusion criteria. FA, rCBF, rCBV, Cho/NAA, Cho/Cr were statistically significant between the two groups (P < 0.05). The sensitivity and specificity of FA, rCBF, rCBV, Cho/NAA, and Cho/Cr in the diagnosis of RT were 70.6%, 97.1%, 91.2%, 91.2%, and 82.4% and 64%, 100%, 100%, 96%, and 72% respectively.ConclusionDTI, DSC, and MRS are of great value in the differential diagnosis of RN and RT of glioma. The diagnostic performance of DSC is better than DTI and MRS.

Diagnostic accuracy of magnetic resonance imaging in detection of intra-axial gliomas

Objective:

To evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) in detection of intra-axial gliomas in suspected cases keeping histopathology as gold standard.

Methods:

This cross-sectional study was conducted at Dow Institute of Radiology, DUHS from October 2017 - April 2018. Patients of either gender aged 30-70 years presenting with headache were included. Patients already diagnosed and referred for follow up were excluded. MRI was performed on 1.5T scanner by a trained MRI technician. T1, T2, FLAIR, diffusion weighted and T1 post contrast images were acquired and reviewed by two radiologists having more than five years post fellowship experience. Sensitivity, specificity, PPV, NPV and diagnostic accuracy of MRI for intraaxial gliomas was calculated taking histopathology findings as gold standard.

Results:

Mean age of the patient`s was 51.71 ±10.85 years. Positive intraaxial gliomas on MRI were observed in 123 (79.90%) patients while on histopathology, positive intraaxial gliomas were observed in 131 (85.10%) patients. Diagnostic accuracy of MRI in detection of intra-axial gliomas taking histopathology findings as gold standard showed sensitivity, specificity, positive predicted value (PPV), negative predicted value (NPV) and overall diagnostic accuracy as 89.31%, 73.91%, 95.12%, 54.84% and 87.01%.

Conclusions:

MRI has high sensitivity, moderate specificity and high diagnostic accuracy in detection of intraaxial gliomas.

Salvage craniotomy for treatment-refractory symptomatic cerebral radiation necrosis

Background

The incidence of symptomatic radiation necrosis (RN) has risen as radiotherapy is increasingly used to control brain tumor progression. Traditionally managed with steroids, symptomatic RN can remain refractory to medical treatment, requiring surgical intervention for control. The purpose of our study was to assess a single institution's experience with craniotomy for steroid-refractory pure RN.

Methods

The medical records of all tumor patients who underwent craniotomies at our institution from 2011 to 2016 were retrospectively reviewed for a history of preoperative radiotherapy or radiosurgery. RN was confirmed histopathologically and patients with active tumor were excluded. Preoperative, intraoperative, and outcome information was collected. Primary outcomes measured were postoperative KPS and time to steroid freedom.

Results

Twenty-four patients with symptomatic RN were identified. Gross total resection was achieved for all patients. Patients with metastases experienced an increase in KPS (80 vs 100, P < .001) and required a shortened course of dexamethasone vs patients with high-grade gliomas (3.4 vs 22.2 weeks, P = .003). RN control and neurological improvement at 13.3 months' follow-up were 100% and 66.7%, respectively. Adrenal insufficiency after rapidly tapering dexamethasone was the only morbidity (n = 1). Overall survival was 93.3% (14/15) at 1 year.

Conclusion

In cases of treatment-refractory symptomatic RN, resection can lead to an overall improvement in postoperative health status and neurological outcomes with minimal RN recurrence. Craniotomy for surgically accessible RN can safely manage symptomatic patients, and future studies assessing the efficacy of resection vs bevacizumab may be warranted.